1. Field of the Invention
This invention relates to a hydraulic shock absorber, the damping force of which is adjustable by operating an actuator from the exterior of the shock absorber.
2. Description of the Prior Art
There are generally known in the art the so-called adjustable damping type hydraulic shock absorbers, which employ a piston rod projected out of a cylinder, an adjusting rod extended through the piston rod, and an actuator for tuning the adjusting rod to adjust the damping force.
The actuator of the hydraulic shock absorbers of this sort is usually in the form of a rotary actuator consisting of a motor and a reducing mechanism or a reciprocating actuator adapted to drive a rack and pinion mechanism by a solenoid. In any case, the actuator itself is considerably large in size and weight.
Therefore, the prior art requires a large space in the axial direction of a hydraulic shock absorber for mounting an actuator on the projected end of a piston rod, and difficulties are often encountered in mounting actuators on vehicles which have only a small mounting space. In a case where a reducing mechanism is used, there arises another problem that mechanical noises are produced during operation. Further, where a stopper of a resilient member is provided in an actuator to limit its operating position, there is the possibility of the actuator's operating position being shifted by bounding movement of the resilient member.